In phased array antennas, a beam can be scanned electronically, that is, by electrical control of an element antenna, with an array antenna device physically fixed. The phased array antennas are therefore capable of quick beam control and multi-beam forming among others. Applications of phased array antennas accordingly include radars and wireless communication. In order to form a desired beam, it is important to calibrate initial fluctuations of a transmission circuit and reception circuit included in each element antenna.
An array antenna device is calibrated usually in an anechoic chamber or at a similar test station with the use of a measuring instrument. A calibration-use antenna is set up at a given distance from the array antenna device so as to face the array antenna device. Calibration is then conducted by connecting the array antenna device and the calibration-use antenna to the measuring instrument. In the case of the calibration of a transmission circuit in the array antenna device, for example, the calibration-use antenna sequentially receives signals transmitted from element antennas, which make up the array antenna device. The signals are detected by the measuring instrument, an arithmetic unit then calculates fluctuations among the signals, and calibration is conducted so as to compensate for the fluctuations. However, equipment investment of the calibration is costly because an anechoic chamber is usually large-scale equipment and the measuring instrument is generally expensive.
Another calibration method in which no calibration-use antenna is positioned so as to face an array antenna device is presented in, for example, Patent Literature 1. This method involves setting up a calibration-use antenna on each side of a linear array antenna to be calibrated, and conducting calibration based on information about signal exchange between the linear array antenna and each calibration-use antenna. The method does not require an anechoic chamber, a measuring instrument, and other pieces of equipment, and accordingly makes it easy to calibrate an array antenna device.